This invention concerns data recording media having embossed features, specifically methods and systems for manufacturing a master disk used to repeatedly replicate such features into mass-produced optical recording disks.
Certain formats for optical disks contain pre-embossed, arc-shaped sector header spokes, as opposed to the straight spokes commonly employed in commercially available optical disks. The shape of the arc is an important factor in the overall design of the data recording system, and therefore it must be formed as accurately as possible.
One aspect of the invention is a process of using a stream of digital bits to produce sector header data on a master recording disk. The header data is in the form of features that correspond to the digital bits. The features are located at varying radial positions on the disk. The process comprises synchronizing the stream of digital bits with rotation of the disk, while introducing between the stream and the rotation a variable delay. The variable delay has a duration that varies with the radial positions of the features on the disk. Thus, the features produced by the data stream form a curved spoke on the disk. The curved spoke can be any convenient shape.
Another aspect of the invention is a method of forming an arced sector header on a rotating master recording disk by using a clock signal. The method comprises introducing into the clock signal a variable delay that preserves the period of the clock signal. The method requires that the period of the clock signal be preserved. The delay may be longer than the period of the clock signal.
Yet another aspect of the invention is a method of using a data stream to form arced sector header shapes on rotating master recording disks. The method utilizes a clock signal having a variable delay that corresponds to a specific sector header shape. The delay preserves the period of the clock signal even though the delay time required to record the sector header may be longer than the period of the clock signal. The specific method comprises modulating a laser light beam by the data stream in response to an incoming data signal generated by a data source. A relative variation between the phase of the data stream and the rotational phase of the rotating master recording disk is created by the clock signal. One of such phases is held constant for each arced sector header shape.
Still another aspect of the invention is a system of forming an arced sector header on a rotating master recording disk. The system uses a data stream and a clock signal. The variable delay preserves the period of the clock signal, even though the delay time required to record the sector header may be longer than the period of the clock signal.
Still another aspect of the invention is a system for using a data stream to form arced sector header shapes on rotating master recording disks. The system uses a data stream having a phase, and the rotating master disk has a rotational phase. A clock signal has a variable delay that corresponds to a specific sector header shape. The system preserves the period of the clock signal, even though the delay time required to record the sector header may be longer than the period of the clock signal. The data stream modulates a laser light beam in response to an incoming data signal generated by a data source. There is a relative variation between the phase of the data stream and the rotational phase of the rotating master recording disk. The system requires that one of such phases is held constant.